Mirror system deficit in ADHD? Study of Mu rhythm suppression during observation and imitation of emotion-related facial movements
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López, Vladimir
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Mirror system deficit in ADHD? Study of Mu rhythm suppression during observation and imitation of emotion-related facial movements
Abstract
Mu rhythm is an EEG oscillatory measure (9 -13 Hz), whose
suppression during movement execution or action observation is
considered an indicator of the activity of the human analog of the
mirror neuron system. Detection of facial emotional expressions
involves detailed observation of facial movements. ADHD is known
to be associated with social cognition impairments, including
emotional face perception, theory of mind deficits and reduced
empathy. The present work compared Mu suppression in 22 ADHD
children and 18 matched control participants (32 % female, ages 9 to
14, Mean 10.8 SD: 1.5), while observing and later imitating the
movements involved in the dynamic unfolding of facial emotion
expressions. Participants observed and imitated facial expressions
performed by actors in 96 short video clips, composed by two
seconds of a neutral face and two seconds where a happy, sad, angry,
or fear expression unfolded. The clip was preceded by a 1 second
fixation cross and followed by a 1 second blank screen. In each trial,
after the observation stage, they were asked for the presence of a
specific emotion, (present in 50% of the trials). Then, they had to
press a key to start co-acting the same facial movements. EEG (40
channels) was recorded using a NeuroScan NuAmps system. Eye
movements were recorded using an Eyelink 1000 system. After
artifact rejection, epochs of -500 ms to 3000 ms were extracted. The
Morlets’ wavelets procedure was used for time frequency analysis
and a -500 to 0 ms window was used as a baseline for Z scoring.
Change in power in the 9-13 Hz band during the 2000 ms window
where movement occurred was used for statistical analysis. Results
showed significant Mu suppression over central regions, more
marked over the left hemisphere, during observation and imitation
(F (1, 38) = 3.07, p b 0.05). Movement execution produced larger
suppressions than observation in Controls. Suppression in the
Control Group was significantly larger than in the ADHD group in
both conditions (F (1, 18) = 6.68, p b 0.01) for all emotional
expressions. Furthermore, observation and imitation did not significantly
differed in the ADHD group. Nevertheless, when comparing
the groups using only those trials in which a significant Mu
suppression occurred no between groups difference was observed.
Lack of suppression in other networks has been reported in ADHD.
This pattern is compatible with a functional, but not structural,
deficit of the mirror system in ADHD.
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CONICYT, FONDECYT
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Artículo de publicación ISI
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URI: https://repositorio.uchile.cl/handle/2250/142295
DOI: 10.1016/j.ijpsycho.2016.07.400
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International Journal of Psychophysiology. Volumen: 108 Páginas: 136-137 Número especial: SI Abstract de reunión: 302
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